Croup
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Introduction
Croup is a viral illness that affects the upper respiratory tract. Also called laryngotracheitis or laryngotracheobronchitis, croup is characterized by symptoms such as a barking cough, stridor, and fever.
Croup most commonly affects children ages 7 months-3 years, and is rare after 6 years of age.
It can occur at any time, though is most common during fall and winter, during the seasons with the most viral infections. The most common pathogen, responsible for more than 75% of infections, is parainfluenza virus.
The Case of Albert P
Albert P is a 2 year-old boy that develops a runny nose and cough. His cough rapidly worsens and becomes bark-like. His mother becomes concerned and brings him to his family physician's office.
- how do you assess Albert?
- what treatments do you consider?
Causes and Risk Factors
Viruses that affect the oropharynx before descending down the airways cause the majority of cases. These include:
- parainfluenza (>75% of cases)
- RSV
- influenza virus
- adenovirus
- paramyxovirus
- rhinovirus
- coxsackievirus
- echovirus
- reovirus
- measles virus
Other causes include bacteria such as:
- Haemophilus influenzae B
- Mycoplasma pneumoniae
Risk factors for developing croup include:
- past history of same
- asthma
- recurrent infections
Pathophysiology
Croup occurs with inflammation and edema that decrease the diameter of the upper airways. This is especially prominent in children, whose airways are small and compliant. Poiseuille's law states that a small decrease in radius causes a significant increase in resistance.
Signs and Symptoms
- history
- physical exam
History
Croup typically presents with prodromal (preceding) upper respiratory symptoms, such as rhinorrhea, pharyngitis, cough, and otalgia.
These progress to cause hoarseness, a barking cough, and stridor.
Symptoms typically are worse at night and improve with the cold; oftentimes, a trip to the hospital will result in resolution of symptoms. Symptoms are also usually worse with agitation.
Physical Exam
Begin by assessing the severity of the child's condition.
- Mild – occasional cough, no stridor, and no respiratory distress (indrawing and accessory muscle use)
- Moderate – frequent barky cough, easily audible stridor at rest, some respiratory distress, but patient is calm
- Severe – frequent barky cough, prominent stridor, significant respiratory distress, and significant distress and agitation
- Impending respiratory failure – barky cough (may be quiet), audible stridor at rest (occasionally hard to hear), sternal wall retractions (may not be marked), lethargy or decreased level of consciousness, and often dusky appearance without supplemental oxygen.
Signs of respiratory illness will be present. Fever is typically not significantly elevated. Tachypnea may be present.
The throat will be red, but exudate is not typical.
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Investigations are not warranted, unless other conditions are suspected.
Diagnostic Imaging
A chest X ray, if performed, may display a 'steeple sign' due to narrowing below the glottis.
Differential Diagnosis
- bacterial tracheitis (serious; similar picture, though with rapid deterioration)
- subglottic stenosis
- foreign body aspiration
- retropharyngeal or peritonsillar abscess
- trauma
- allergic reaction/anaphylaxis
- congenital airway anomalies
- epiglottitis
- subglottic hemangioma
Treatments
Treatment includes:
- humidified oxygen
- dexamethasone, orally, x1 dose
- racemic epinephrine hourly x1-3 doses; observe for rebound effects
- intubation may be required if treatment is not helpful
Consequences and Course
Croup typically is mild and responds to medical therapy. However, as described, lifesaving intubation is occasionally necessary.
Resources and References
AlbertaDoctors.org - Guidelines for the Diagnosis and Management of Croup
Topic Development
authors: Sept 11, David LaPierre
reviewers:
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